1. Field of the Invention
The present invention relates to the field of diagnostic methods and apparatuses for computer systems. More specifically, this invention relates to a device and method for diagnosing a faulty computer system without disassembling the system.
2. Description of Related Art
The diagnosis of faulty computer systems, at times, can be a difficult process. For systems which are incapable of powering up and performing a system bootstrap initialization process, determining which components are faulty requires substantial time and effort using a variety of methods. One method of diagnosing a faulty computer system is to remove components in the computer system one by one and replace them with components which are known to work. Such a "trial and error" approach not only requires an on-hand inventory of components which are functional, but also requires that the computer system be disassembled. This type of diagnosis requires substantial effort to disassemble and reassemble the system and does not necessarily identify the underlying detect which caused the failure.
Yet another method for diagnosing a faulty computer system is to couple various types of diagnostic apparatuses to individual components. This process requires some disassembly of the computer system to attach diagnostic probes to the individual components. Depending on the location of individual components, this process may take a lot of time to disassemble the faulty device. This also requires specialized tools to test individual components.
For a system which is able to power up and execute a system bootstrap initialization but does not function properly, diagnosis may be performed using a software utility. Some types of utility programs may diagnose certain faulty components, but if the faulty components are required to operate the utility, the diagnosis of the system will be impossible. Even though the disassembly of the computer system may not be required to run such a diagnostic program, this program may be limited by the inability to test certain hardware components.
Some computer systems perform a software diagnostic self-test upon a system bootstrap initialization process. This type of routine tests various components in the system prior to operation to ensure that the system is operating properly. One such diagnostic routine is known as the "Test Manager" program which forms part of the bootstrap initialization procedure of the Macintosh.RTM. brand computer available from Apple Computer, Inc. of Cupertino, Calif. (Macintosh.RTM. is a trademark of Apple Computer, Inc.). This initialization process includes, among other things, initializing versatile interface adaptor (VIA) circuits, serial communication controller (SCC) circuits, floppy disk drive integrated circuit controllers, small computer system interface controller (SCSI) circuits, and sound device circuits coupled to the system. These routines, which are embedded in read-only memory (ROM)contained within the system, require that the system be capable of activating system power and initializing. If the system cannot be initialized, then certain types of tests may not be able to be performed.
Another drawback of prior approaches to diagnosing computer systems is that different computer systems have a variety of interfaces and ports. Each port or interface requires a different connector and/or different circuitry to test these ports or interfaces. For instance, in addition to generic serial and parallel ports such as RS-232 standard ports or SCSI ports, some computer systems may have manufacturer-specific ports such as the Apple Desktop Bus (ADB) brand interface manufactured by Apple Computer, Inc. The wide variety of ports, interfaces and other coupling means for various systems makes it difficult to diagnose the many types of computer systems in the marketplace. Because the parameters of each interface and/or port must be known to the individual diagnosing the computer system, it is difficult for one person to diagnose a variety of machines. In addition, it is helpful if various types of connectors are available for coupling to the various systems for diagnosis. In summary, no single device possesses the necessary characteristics to diagnose various types of computer systems at all levels of operation.